The "dish mic" I made used an 18' serving bowl, obtained for next to nothing at a garage sale, as the parabola. It works better, but took a little crafting to install the bolt to support the $30 lavelier that sits at the parabolic focus. I find it easier to connect it to a digital sound recorder than to encumber the camera. Dual audio capture helps if you don't know where the critters are in advance.